Face Seal Feed-Slot Geometry for Lower Closing Force
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Solution Overview
Problem
High contact pressure and net closing force in existing face seal arrangements for gas turbine engines lead to increased heat generation, friction losses, and reduced service life.
Innovation Solution
A face seal arrangement with a non-rotating sealing ring and a seal housing biased by a coil spring, featuring circumferentially spaced feed slots connected to annular grooves, which communicate high-pressure air to reduce contact pressure and net closing force, utilizing a geometric design with optimized ratios of feed depth to axial nose extension and feed slot length to axial nose thickness to maintain an appropriate seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high contact pressure and net closing force are used in face seal arrangements, then sealing effectiveness is improved, but heat generation and friction losses increase
Solution Approach 1:
The patent introduces pressurized air through feed slots and annular grooves to create a pneumatic cushion between the sealing face and seal seat. This air pressure reduces the contact pressure and net closing force, thereby decreasing friction losses and heat generation while maintaining adequate sealing effectiveness through controlled air pressure and geometric design
2Reliability
If high contact pressure is applied to the face seal, then sealing reliability is improved, but heat generation increases
Solution Approach 1:
Pressurized air delivered through the feed slots and annular grooves creates a thermal cushion that reduces direct contact heat generation. The pneumatic pressure distribution system lowers the contact pressure between sealing surfaces, thereby reducing friction-induced heat while maintaining sealing reliability
3Reliability
If high net closing force is used in face seal arrangements, then sealing performance is improved, but service life is reduced
Solution Approach 1:
The pneumatic pressure system reduces the net closing force by introducing pressurized air that counteracts the spring force. This decreases the overall load on the sealing components, reducing wear and extending service life while maintaining adequate sealing performance through optimized air pressure and geometric design parameters
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces contact pressure and net closing force, enhancing the service life of face seals and minimizing engine friction losses and heat generation.
Implementation Method 1
A coil spring biases the seal housing towards the seal seat
Implementation Method 2
High pressure air from outside the bearing compartment is communicated through the plurality of circumferentially spaced feed slots to the at least one annular groove
Data Source
AI summary
A bearing is mounted to a static structure outwardly of the shaft, and supporting the shaft. A bearing compartment is defined by face seal arrangements on each of two axial sides of a bearing. Each face seal arrangement includes a seal seat rotating with the shaft and a non-rotating sealing ring. The seal housing is exposed to high pressure air outward of the bearing compartment. A coil spring biases the seal housing towards the seal seat, such that the sealing face is biased into contact with the seal seat by a bias force including a net fluid force acting on the seal housing and the coil spring. The sealing face is defined by a contact portion contacting the seal seat and a feed portion recessed from the seal seat. The feed portion includes a plurality of circumferentially spaced feed slots fluidly connected to at least one annular groove.